Case Interview Cheat Sheet: Frameworks, Math Formulas, and Quick Reference (2026)
Mar 20, 2026
Fundamentals · Case Interview, Frameworks, Math
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Published Mar 20, 2026
Summary
Bookmark this cheat sheet: all major case frameworks, essential math formulas, mental math shortcuts, and quick-reference tips for consulting interviews.Seven frameworks, 12 math formulas, and mental math shortcuts — everything you need for case interviews at McKinsey, BCG, and Bain on one page. Case interviews test structured thinking (frameworks), quantitative reasoning (math), and communication (delivery). You cannot bring this sheet into an interview — the goal is to internalize it through repeated review and practice until every formula and framework element is automatic recall.
A case interview cheat sheet is a condensed reference of the frameworks, formulas, and mental models used in management consulting interviews. Internalize its contents through practice — do not attempt to memorize verbatim, as interviewers penalize candidates who recite pre-built frameworks.
Knowing the frameworks is step one — applying them is step two
Practice cases with AI coaching that evaluates your framework choice, math accuracy, and structured delivery.
Try a free caseThe 7 Core Frameworks
Every case can be structured using elements from these frameworks. The key word is "elements" — build a custom structure for each case using relevant building blocks, never apply any framework verbatim. McKinsey, BCG, and Bain all penalize framework recitation (Source: IGotAnOffer 2025).
| Framework | When to Use | Core Question |
|---|---|---|
| Profitability | Profit declining | Revenue problem, cost problem, or both? |
| Market Entry | New market/product | Market size, competition, capabilities, economics? |
| M&A | Acquisition decision | Strategic fit, financials, integration risks? |
| Pricing | Price setting/change | Cost-plus, value-based, or competitive? |
| 3Cs | Broad strategy | Company, Customers, Competition? |
| 4Ps | Go-to-market | Product, Price, Place, Promotion? |
| Porter's Five Forces | Industry analysis | Supplier/buyer power, substitutes, entrants, rivalry? |
Profitability is the most common type. Equation: Profit = Revenue - Costs. Break revenue into Price x Quantity by segment; costs into Fixed + Variable. Key diagnostic: is this industry-wide or company-specific?
Porter's Five Forces measures industry attractiveness. High supplier/buyer power, substitutes, new entrants, or rivalry reduce profitability.
The 12 Essential Math Formulas
These formulas appear repeatedly across case interviews. You must apply each from memory without a calculator. Every profitability case uses the first three; break-even and contribution margin appear in market entry and pricing cases.
| Formula | Equation | When to Use |
|---|---|---|
| Profit | Revenue - Costs | Every profitability case |
| Revenue | Price x Quantity | Revenue driver breakdown |
| Break-even (units) | Fixed Costs / (Price - Variable Cost) | New products, market entry |
| Profit Margin | (Profit / Revenue) x 100 | Cross-segment comparison |
| Market Share | Company Rev / Total Market Rev | Market analysis |
| CAGR | (End / Start)^(1/n) - 1 | Multi-year growth |
| ROI | (Gain - Cost) / Cost x 100 | Investment decisions |
| NPV (perpetuity) | Annual Cash Flow / Discount Rate | Valuation |
| Payback Period | Investment / Annual Cash Flow | Investment recovery |
| Contribution Margin | Price - Variable Cost | Pricing, product profit |
| Customer Lifetime Value | Avg Revenue x Avg Lifespan | Customer economics |
| Price Elasticity | % Change Qty / % Change Price | Pricing impact |
Worked Example: Multiple Formulas Applied
Scenario: A SaaS company charges $200/month per user with 50,000 users. Variable cost: $60/user. Fixed costs: $4.2M/month. They consider a price decrease to $180, estimated to increase users by 20%.
Current state:
- Revenue = $200 x 50,000 = $10M/month
- Profit = $10M - ($60 x 50,000) - $4.2M = $2.8M/month
New scenario:
- Users = 50,000 x 1.20 = 60,000
- Revenue = $180 x 60,000 = $10.8M/month
- Profit = $10.8M - ($60 x 60,000) - $4.2M = $3.0M/month
Verdict: Profit increases $200K/month (+7.1%). The 20% volume increase more than offsets the 10% price reduction. Contribution margin check: extra 10,000 users x $120 = $1.2M exceeds margin loss on existing users of 50,000 x $20 = $1.0M.
Mental Math Shortcuts
No calculators allowed in case interviews. These shortcuts make math fast and reliable under pressure. Practice daily for 2 weeks until each technique is automatic (Source: Hacking the Case Interview 2025).
| Shortcut | Method | Example |
|---|---|---|
| Multiply by 5 | Divide by 2, add zero | 840 x 5 = 420 x 10 = 4,200 |
| Percentages | Combine 10% and 5% | 15% of 6,400 = 640 + 320 = 960 |
| Rule of 72 | 72 / growth rate = years to double | 8% growth: doubles in 9 years |
| Simplify then adjust | Round, calculate, correct | 49 x 32: 50 x 32 = 1,600 - 32 = 1,568 |
| Divide by 8 | Halve three times | 4,800 / 8 = 2,400 / 2 = 1,200 / 2 = 600 |
| Large multiplication | Break into parts | 370 x 24 = 7,400 + 1,480 = 8,880 |
For the full guide, see mental math for case interviews.
Formulas memorized? Test them under pressure
Case interview math is not hard — it is hard under pressure. Practice timed calculations with AI that coaches your speed and accuracy.
Case Structure and Synthesis Templates
Structuring a case (first 60-90 seconds): Restate the question and confirm the objective. Identify 3-4 MECE buckets covering key investigation areas. State which bucket to explore first and why. Verify: no overlap between buckets, nothing important missing. See our MECE principle guide.
Synthesis (final 30-60 seconds): "I recommend [action]. Three findings support this: [1], [2], [3]. The main risk is [risk], mitigated by [action]. Next step: [action]." See our synthesis guide.
| Case Type | First Question to Ask | Key Formula |
|---|---|---|
| Profitability decline | Revenue problem, cost problem, or both? | Profit = Revenue - Costs |
| Market entry | What is the market size and growth rate? | Break-even = Fixed Costs / Contribution Margin |
| Pricing | What is the customer's willingness to pay? | Value vs. price vs. competitor price |
| M&A | What is the strategic rationale? | NPV = Cash Flow / Discount Rate |
| Growth strategy | Organic or through acquisition? | CAGR = (End/Start)^(1/n) - 1 |
| Market sizing | What is the base population or unit? | Population x Filters x Frequency x Price |
Common Mistakes to Avoid
Reciting a framework verbatim is penalized at McKinsey, BCG, and Bain — build custom structures using framework elements as building blocks. Jumping to math before understanding the problem wastes time on the wrong question. Calculating silently prevents the interviewer from following your logic and correcting errors.
Forgetting to sanity-check catches errors before the interviewer does — if a coffee shop's annual revenue calculates to $50M, something is wrong. Giving recommendations without data support ("I think they should enter the market") scores poorly.
Always narrate your math: "Fixed costs are $2M. Contribution margin is $50/unit. Break-even = $2M / $50 = 40,000 units." This lets the interviewer follow your logic, correct small mistakes, and evaluate your structured reasoning — which matters as much as the final answer.
Related Guides
- Case interview frameworks complete guide — deep dive into all frameworks with examples
- Consulting math formulas — extended formula list with worked examples
- Case interview math practice — timed drills for every formula
- Mental math for case interviews — speed techniques beyond this sheet
- MECE principle explained — the organizing principle behind every framework
- Case interview opening statement — how to present your structure in 90 seconds
- Case interview tips and mistakes — errors that eliminate candidates
Test Your Knowledge
Test yourself
Question 1 of 3
QuizWhat is the break-even formula for a new product?
You have the formulas — now apply them under pressure
Case interviews test whether you can use frameworks and math in real time, under pressure, while communicating clearly. Practice with AI coaching that scores all three.
Sources (checked March 20, 2026)
- Hacking the Case Interview frameworks guide: https://www.hackingthecaseinterview.com/pages/case-interview-frameworks
- Hacking the Case Interview cheat sheet and study guide: https://www.hackingthecaseinterview.com/pages/case-interview-cheat-sheet-study-guide
- Hacking the Case Interview 26 essential formulas: https://www.hackingthecaseinterview.com/pages/case-interview-formulas
- Management Consulted case interview formulas: https://managementconsulted.com/case-interview-formulas/
- IGotAnOffer case interview frameworks guide: https://igotanoffer.com/blogs/mckinsey-case-interview-blog/118288068-case-interviews-frameworks-comprehensive-guide
- CaseBasix case interview cheat sheet guide: https://www.casebasix.com/pages/case-interview-cheat-sheet-guide
- IGotAnOffer case interview math guide: https://igotanoffer.com/blogs/mckinsey-case-interview-blog/case-interview-maths
Frequently asked questions
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